Search results for "Light"

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

2000

The influence of substitution on the absorption and Luminescence spectra of oligo(phenylenevinylene)s has been studied using distyrylbenzene (DSB) as a model compound. The degree, character, and pattern of substitution was varied systematically, altering the electronic properties of the DSB, the wavelength of the emitted light could be tuned over a range of 100 nm. The syntheses of 6b—h were performed by twofold Wittig Horner-olefinations of bisphoshonates 1a, b with substituted benzaldehydes 2a—i, 6ivia Heck-reaction of the dibromosulfonylbenzene 3, 6k by Siegrist-reaction of 4 with N-phenylbenzaldimine and the Knoevenagel-reaction of benzyl cyanide with 5 led to 6l.

Corrigendum to “Light-induced, site-selective isomerization of glyoxylic acid in solid xenon” [Chem. Phys. Lett. 616–617 (2014) 91–97]

2015

Comparison of the Effects of Indole-3-Acetic Acid and Kinetin on the Photosynthetic Apparatus and on the Cell Metabolism

1984

External and internal factors can exert a regulatory influence on growth and differentiation within a reaction norm determined by the genetic material. As to the internal factors, the phytohormones intervene in the most development processes in a regulatory manner. In a number of publications it was pointed out that there is a far-reaching accordance between the effects caused by I.4A and the effects induced by red light and low light conditions (Zerbe, Wild, 1980 a; Holzapfel et al., 1982 a). Plants of Sinapis alba grown under low light conditions but additionally treated with kinetin show changes in their metabolism that are characteristic of plants grown at higher light intensities (Zerb…

1984

By means of data from critical demixing and vapour pressure measurements and by inverse gas chromatography, including the results of published light scattering measurments, a consistent picture is obtained for the entire dependence of the Flory-Huggins parameter χ on the weight fraction w2 of the polymer and on the temperature T for the system tert-butyl acetate/polystyrene. Within the entire T-range (ca. 0°C – 140°C), χ increases stronger than exponentially with w2, the rise being the larger the larger χH (the enthalpy contribution to χ) becomes in the limit of infinite dilution. At sufficiently high temperatures (≳ 50°C), χH changes its sign from negative to positive as w2 is raised. This…

Photo-Crosslinking of Copolymeric Methacrylates Bearing Stilbene Chromophores

2012

Radical polymerization of methyl methacrylate (2) as major component and the methacrylates 1a or 1b, which contain an (E)-stilbene unit fixed by a tether to the ester group, yield easily soluble copolymers 3a, b. Whereas the dominant photoreactions in solution are (E)⇄Z) isomerizations and intra-chain [2π +2π] cycloadditions, cast films of 3a, b give an inter-chain photo-crosslinking on irradiation. Compared to homopolymers, the copolymers are not only better soluble and more easily processible, their films show less undesired light scattering. The cross-linked material is completely insoluble in organic solvents. Thus, it represents the basis for negative photoresists and the corresponding…

Metal Dependence on the Bidirectionality and Reversibility of the Singlet Energy Transfer in Artificial Special Pair-Containing Dyads

2017

International audience; The demetalation of a precursor dyad, 3, built upon a zinc(II)-containing artificial special pair and free-base antenna, leads to a new dyad, 4, for singlet energy transfer composed of cofacial free-base porphyrins (acceptor), [Fb](2) bridged by a 1,4-C6H4 group to a free-base antenna (donor), [Fb]. This dyad exhibits the general structure [M](2)-C6H4-[Fb], where [M](2) = [Fh](2), and completes a series reported earlier, where [M](2) = [Mg](2) (2) and [Zn](2) (3). The latter dyads exhibit a bidirectional energy-transfer process at 298 K for 2 and at 77 K for 3. Interestingly, a very scarce case of cycling process is observed for the zinc-containing dyad at 298 K. The…

Oggetti interni e reaction objects come nomi predicativi di costrutti a verbo supporto

2011

Analyses regarding clauses with a cognate object (CO), e.g. Alice laughed a scornful laugh, have frequently been based on the query: is the CO an adjunct or a complement? This paper aims to contribute to the debate with an alternative suggestion: the CO functions as a noun predicate licensing the subject, to which it assigns a semantic role, whilst the verb functions as a support (a ‘light verb’). A number of the well-known properties of COs, e.g. certain constraints on the determiner, appear to corroborate this analysis. Clauses with the so-called reaction object (RO), e.g. Alice coughed a scornful laugh, are analyzed as multi-predicative as well: also the RO is a noun predicate which lice…

Pour une approche cognitive et multiscalaire des conflits environnementaux

2011

Starting with artificial light as new object damage and emerging environmental problem, this paper intends to develop a general reflection showing the importance of a greater consideration of cognitive dimensions of the damage and risk analysis in environmental conflicting processes. We show how the cost-benefit analysis after the neoclassical theory of production, often used in the search for Pareto-optimal state and in the policies of monetary compensation to resolve environmental conflicts can - indeed must - be strongly challenged. Also, with this reasoning, we oppose an analysis in terms of cognitive interactions that groups develop around environmental goods and items of damage, thus …

A Methodology for Protection of Trees Against Lightning Strikes as a Measure to Prevent Fires and Loss of Human Life

2021

Some regions may be characterized by a very low annual lightning ground flash density, and yet lightning strikes seem to have been in those areas the cause of widespread wildfires in forested areas. Due to global climate change, these occurrences seem to be an increasing threat. In this paper, the authors discuss the withstand capability of trees against lightning and introduce the criteria for the deployment of tree lightning protection systems (TLPS) to protect forested areas, where deemed necessary by the tree risk assessment. This work analytically identifies the critical trunk radius of the tree below which the tree may explode in the case of a lightning strike and ignite the surroundi…

RScriptsCommonRosefinch

2021

Lisovski S, Neumann R, Albrecht T, Munclinger P, Ahola M, Bauer S, Cepak J, Fransson T, Jakobsson S, Jaakkonen T, Klvana P, Kullberg C, Laaksonen T, Metzger B, Piha M, Shurulinkov P, Stach R, Strom K, Velmala W, Briedis M. 2021. The Indo-European Flyway: opportunities and constraints reflected by common rosefinches breeding across Europe. J Biogeogr. doi:10.1111/jbi.14085